In EPS (Evolved Packet System), E-UTRAN (Evolved Universal Terrestrial Radio Access Network) capable terminals are allocated a default bearer during the attach procedure. This default bearer provides always-on IP connectivity to a PDN (Packet Data Network). If these terminals attach to their Home PLMN, then they will be allocated a default bearer to access a PDN in Home PLMN.
FIG. 1 illustrates a UE (User Equipment) 2 attached to a HPLMN in a Network architecture comprising a (Mobility Management Entity) MME 4, a Home Serving Gateway 6, and a (Evolved Universal Terrestrial Radio Access Network access network) E-UTRAN 8. The MME is connected to a HSS and the Home Serving Gateway 6 is connected to a PDN Gateway 12 of said HPLMN. The PDN Gateway 12 connects the UE 2 to an operator IP service 14 such as IMS or PSS.
A default bearer 16 is established in Home PLMN in order to allow the UE 2 to access to said operator IP services 18.
FIG. 2 illustrates the case where the UE 2 roams from its HPLMN to a VPLMN.
In this situation, the UE 2 connects to the PDN Gateway 12 and to a PDN Gateway Visited PLMN 20 through a Visited Serving Gateway 22.
A default bearer to visited PDN 24 is established in the VPLMN in order to allow the UE 2 to Visited operator IP services 26. According to the current 3GPP recommendations, one possibility to establish connectivity to the PDN different from default PDN is to use procedure for UE requested PDN connectivity as described below with reference to FIG. 3 describing current state of the art for a UE roaming in a Visited PLMN and asking for extra PDN connectivity further to the Tracking Area Update procedure. It is assumed that this can be the procedure used for local breakout, as described in 3GPP document S2-074760.
When the UE 2 moves to a new Tracking Area, it sends a TAU Request (step 30) to an eNodeB 32. This eNodeB 32 transmits (step 34) said TAU Request to a new MME 36. The new MME 36 sends (step 38) a Context Request to the old MME 40 which responds (step 42) to the new MME 36 by a Context Response.
After authentication of the UE 2 (step 44), the new MME 36 transmits (step 48) a Context Acknowledge to the old MME 40.
At step 50, the new MME 36 transmits a Create Bearer Request to a new serving Gateway 52 which transmits (step 54) an Update Bearer Request to a PDN Gateway 56 in Home PLMN. The PDN Gateway 56 transmits an Update Bearer Request (step 56) to the new serving Gateway 52. Said new serving Gateway 52 transmits a Create Bearer Response (step 58) to the new MME 36.
The later transmits an Update Location (step 60) to a HSS 62 (Home Subscriber Server).
At step 64, the HSS 62 transmits a Cancel Location message to the old MME 40.
At step 66, the old MME 40 responds to the HSS 62 by a Cancel Location ack.
At step 68, the HSS 62 transmits to new MME 36 a request Insert Subscriber Data (IMS, subscriber data).
At step 70, the new MME 36 transmits to HSS 62 a request Insert Subscriber Data Ack.
At step 72, the HSS 62 transmits to the new MME 36 an Update Location Ack.
At step 74, the old MME 40 transmits to the old serving Gateway 76 a Delete Bearer Request.
At step 78, the old serving Gateway 76 transmits to the old MME 40 a Delete Bearer Response.
At step 80, the new MME 36 transmits to the UE 2 a TAU (Tracking Area Update Accept).
At step 82 the UE 2 transmits to the new MME 36 a TAU complete message.
At step 90, the UE 2 requests the setting of a new PDN connection in the VPLMN and sends, at step 92, a PDN connectivity request to the new MME 36.
At step 94, the new MME 36 transmits to the new serving gateway 52 a Create Default Bearer Request.
At step 96, new serving gateway 52 transmits to a PDN Gateway 98 in the VPLMN a Create Default Bearer Request.
At step 98, the PDN Gateway may interact with the PCRF (Policy and Charging Rule Function) to get the default PCC (Policy, Control and Charging) rules for the UE.
At step 100, the PDN Gateway 98 transmits to the new serving gateway 52 a Create Default Bearer Response.
At step 102, the new serving gateway 52 transmits to the new MME 36 a Create Bearer Response.
The new MME 36 transmits, at step 104, a Bearer Setup Request to the eNodeB 32.
At step 106, the eNodeB 32 transmits to the UE 2 a Radio Bearer Establishment Request.
At step 108, the UE 2 transmits to the eNodeB 32, a Bearer Setup Response.
At step 110, the eNodeB 32 transmits to the new MME 36 a Bearer Setup Response.
The new MME 36 transmits, at step 112, to the new serving gateway 52, an Update Bearer Request.
As can be seen in FIG. 3, the PDN connectivity to a new PDN can be established by the UE 2 in order to do local breakout, but this requires an explicit standalone procedure (steps 90 to 112).
However, using this procedure would mean that it is up to the UE (User Equipment) to setup this PDN connectivity when the UE roams in a Visited PLMN. In addition, it is not described in current 3GPP specification how and when the connection to a PDN in Visited PLMN is performed while maintaining a connection to a PDN in Home PLMN.
An object of the present invention is to provide means for establishing the connectivity to a PDN in Visited PLMN as soon as the UE enters this Visited PLMN from another PLMN. This last PLMN can be Home PLMN or another Visited PLMN.